[NETFILTER] arp_tables: Fix unaligned accesses.

There are two device string comparison loops in arp_packet_match().
The first one goes byte-by-byte but the second one tries to be
clever and cast the string to a long and compare by longs.

The device name strings in the arp table entries are not guarenteed
to be aligned enough to make this value, so just use byte-by-byte
for both cases.

Based upon a report by <drraid@gmail.com>.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 7 deletions

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 5170f5c75f9d..57b0221f9e24 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -166,13 +166,9 @@ static inline int arp_packet_match(const struct arphdr *arphdr,
                 return 0;
         }
 
-        for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned long); i++) {
-                unsigned long odev;
-                memcpy(&odev, outdev + i*sizeof(unsigned long),
-                       sizeof(unsigned long));
-                ret |= (odev
-                        ^ ((const unsigned long *)arpinfo->outiface)[i])
-                        & ((const unsigned long *)arpinfo->outiface_mask)[i];
+        for (i = 0, ret = 0; i < IFNAMSIZ; i++) {
+                ret |= (outdev[i] ^ arpinfo->outiface[i])
+                        & arpinfo->outiface_mask[i];
         }
 
         if (FWINV(ret != 0, ARPT_INV_VIA_OUT)) {